Allergen Challenge In Mice Research Articles

Platelets Independently Recruit into Asthmatic Lungs and Models of Allergic Inflammation via CCR3.

Platelet activation and pulmonary recruitment occur in patients with asthma and in animal models of allergic asthma, in which leukocyte infiltration, airway remodeling, and hyperresponsiveness are suppressed by experimental platelet depletion. These observations suggest the importance of platelets to various characteristics of allergic disease, but the mechanisms of platelet migration and location are not understood. The aim of this study was to assess the mechanism of platelet recruitment to extravascular compartments of lungs from patients with asthma and after allergen challenge in mice sensitized to house dust mite (HDM) extract (contains the DerP1 [Dermatophagoides pteronyssinus extract peptidase 1] allergen); in addition, we assessed the role of chemokines in this process. Lung sections were immunohistochemically stained for CD42b+ platelets. Intravital microscopy in allergic mice was used to visualize platelets tagged with an anti–mouse CD49b-PE (phycoerythrin) antibody. Platelet–endothelial interactions were measured in response to HDM (DerP1) exposure in the presence of antagonists to CCR3, CCR4, and CXCR4. Extravascular CD42b+ platelets were detected in the epithelium and submucosa in bronchial biopsy specimens taken from subjects with steroid-naive mild asthma. Platelets were significantly raised in the lung parenchyma from patients with fatal asthma compared with postmortem control-lung tissue. Furthermore, in DerP1-sensitized mice, subsequent HDM exposure induced endothelial rolling, endothelial adhesion, and recruitment of platelets into airway walls, compared with sham-sensitized mice, via a CCR3-dependent mechanism in the absence of aggregation or interactions with leukocytes. Localization of singular, nonaggregated platelets occurs in lungs of patients with asthma. In allergic mice, platelet recruitment occurs via recognized vascular adhesive and migratory events, independently of leukocytes via a CCR3-dependent mechanism.

In utero Exposure to Nicotine Containing Electronic Cigarettes Increases the Risk of Allergic Asthma in Female Offspring.

E-cigarettes (eCig) are being considered as an alternative to quit cigarette smoking while their long-term effect on lung pathophysiology are unknown. Maternal eCig-vaping may be promoted and considered as a safer cigarette smoking-replacement during pregnancy thus needing further assessment. Using murine models of in utero vaping and allergic asthma with complementary in vitro experiments we tested whether maternal eCig vaping enhances features of allergic asthma in offspring. Female BALB/c mice were exposed to either eCig vapor (± nicotine) or room air. Female offspring from these mothers were subjected to an ovalbumin (OVA)-induced allergic asthma model. Lung function and airway inflammation was assessed. Tissues were histologically assessed with H&E, Periodic Acid-Schiff and Masson's trichrome. Mitochondrial homeostasis protein expression was measured using immunohistochemistry while human airway smooth muscle (ASM) and Beas-2B cells were used to further measure cellular function and mitochondrial respiration. Allergen-challenge in mice lead to significant increase in airway inflammation, development of airway hyperresponsiveness (AHR) and increase in mucus and airway wall thickening (hallmark features of allergic asthma). Allergic asthma features were significantly enhanced in offspring from eCig (+Nicotine)-exposed mothers and were mainly reliant upon Th2-dependent inflammation with complementary changes in mitochondrial homeostasis. Further, in vitro data demonstrated that eCig (±Nicotine)-exposure impaired airway cell homeostasis and perturbed mitochondrial function. Collectively, maternal eCig vaping enhanced and worsened features of allergic asthma and this could partly be attributed to aberrant mitochondrial function.

House Dust Mite-Induced Allergic Airway Disease Is Independent of IgE and FcεRIα.

IgE contributes to disease exacerbations but not to baseline airway hyperresponsiveness (AHR) in human asthma. In rodent allergic airway disease (AAD), mast cell and IgE dependence for the induction of AHR has only been observed when mice are immunized with a relatively weak allergen without adjuvant. To evaluate the role of IgE in murine AAD that is induced by a potent allergen, we inoculated BALB/c and FVB/N background wild-type and IgE- or FcεRIα-deficient mice intratracheally with large or limiting doses of house dust mite extract (HDM) and evaluated AHR, pulmonary eosinophilia, goblet cell metaplasia, serum IgE, and lung mastocytosis. We found that neither IgE nor FcεRIα contributed to AAD, even in mice inoculated with the lowest dose of HDM, which readily induced detectable disease, but did not increase serum IgE or pulmonary mast cell levels. In contrast, high doses of HDM strikingly increased serum IgE and pulmonary mast cells, although both AHR and airway mast cell degranulation were equally elevated in wild-type and IgE-deficient mice. Surprisingly, allergen challenge of mice with severe AAD and pulmonary mastocytosis failed to acutely increase airway resistance, lung Newtonian resistance, or hysteresis. Overall, this study shows that, although mice may not reliably model acute asthma exacerbations, mechanisms that are IgE and FcεRIα independent are responsible for AHR and airway inflammation when low doses of a potent allergen are inhaled repetitively.

Therapeutic Potential of Monoclonal IgA Antibodies in Allergic Diseases: Suppressive Effect of IgA on Immune Responses Induced By Re-exposure to Antigen in Sensitized Mice by Monoclonal IgE Antibody That Binds to a Different Epitope of the Same Antigen

Repeated exposure to an allergen induces allergic symptoms by activating mast cells that express anti-allergen IgE, which results in further sensitization to an allergen. Considering that additional sensitization elicits more severe allergic reactions upon the next allergen challenge, suppression of the boosting phase represents an efficacious way to prevent and ameliorate allergic diseases. In this study, we investigated the therapeutic potential of allergen-specific monoclonal IgA on allergic diseases. This antibody acts by decreasing immune responses upon exposure to allergens in mice previously sensitized by a monoclonal IgE that recognizes the allergen. The lack of inhibitory effects of anti-ovalbumin monoclonal IgA (OA-4) on either the binding of anti-ovalbumin monoclonal IgE (OE-1) to ovalbumin by ELISA or on ovalbumin-induced degranulation of rat basophilic leukemia RBL2H3 cells sensitized with OE-1 indicated that OA-4 and OE-1 recognized different epitopes on ovalbumin. Immune responses (anti-ovalbumin IgG1 production and cytokine release from splenocytes) induced by intravenous ovalbumin challenge in DBA/1J mice passively sensitized with OE-1 were inhibited by intravenous injection of OA-4 15 min before challenge without affecting anaphylaxis. Moreover, OA-4 injection 1 h after ovalbumin challenge also effectively suppressed immune responses. The achievement of immunosuppression by IgA injection occurred even after allergen challenge in mice in an epitope-independent fashion. These findings suggest that monoclonal IgA administered at the time of hospitalization of a patient with allergic symptoms, who was already exposed to the allergen in the presence of IgE recognizing an undefined epitope(s) on the allergen, should effectively relieve allergic disease through its immunosuppressive effects.

Mast cells present protrusions into blood vessels upon tracheal allergen challenge in mice.

Mast cells (MC) and myeloid dendritic cells (DC) act proximally in detecting and processing antigens and immune insults. We sought to understand their comparative dynamic behavior with respect to the airway epithelium in the steady state and in response to an allergic stimulus in mouse trachea. We devised methods to label MC in living trachea and to demonstrate that MC and DC occupy distinct layers of the tracheal mucosa, with DC being closer to the lumen. DC numbers doubled after allergen challenge, but MC numbers remained stable. MC and DC migrated minimally in either steady state or allergen-challenge conditions, and their interactions with one another appeared to be stochastic and relatively infrequent. While DC, unlike MC, exhibited probing behaviors involving dendrites, these projections did not cross the epithelium into the airway lumen. MC typically were located too far from the epithelial surface to contact the tracheal lumen. However, MC had protrusions toward and into blood vessels, likely to load with IgE. Thus, DC and MC occupy distinct niches and engage in sessile surveillance in the mouse trachea. Little or no access of these cell types to the airway lumen suggests that trans-epithelial transport of proteins in the steady state would be required for them to access luminal antigens.

Expression of neuronal protein Kidins220/ARMS in the spleen and peripheral blood of mice following airway allergen challenge

Nerve growth factor (NGF), combined with the high-affinity tyrosine kinase receptor A (TrkA), has been reported to be involved in the pathogenesis of asthma. Ankyrin-rich membrane spanning/transmembrane substrate of protein kinase D (ARMS/Kidins220), a TrkA‑binding protein, modulates the NGF signaling pathway. The aim of the present study was to investigate the expression of Kidins220/ARMS and the effect NGF has on the protein in the spleen and peripheral blood, following airway allergen challenge in mice. BALB/c mice were sensitized and challenged with ovalbumin. The effects of NGF on Kidins220/ARMS in the spleen and peripheral blood of mice were assessed by administering anti-NGF antibody. Expression of ARMS, interleukin (IL)-1β and IL-4 in the spleen and peripheral blood was observed by reverse transcription-polymerase chain reaction, western blot analysis and immunohistochemistry. Pathological changes in the bronchi and lung tissues were examined by hematoxylin and eosin staining. Results showed that Kidins220/ARMS, IL-1β and IL-4 were overexpressed in the spleen and peripheral blood following allergen challenge, compared with the control mice. Moreover, following treatment with anti-NGF, the levels of Kidins220/ARMS, IL-1β and IL-4 in the mice were downregulated. Therefore, the results of the present study showed that Kidins220/ARMS is expressed in the spleen and peripheral blood of normal BALB/c mice and may participate in the immuno-inflammation of asthma through the NGF-mediated signaling pathway.

Chemokine Complexity

William of Ockham (of Ockham's Razor fame) and Albert Einstein both urged us to keep it simple, but biology, perhaps in comparison to philosophy or physics, is often a more complicated matrix. An example of the complex nature of nature is the case of chemokine action in mediating inflammatory disease. Thus, chemokines were associated initially with the development of inflammatory and allergic disease primarily through their role as chemoattractant cytokines. In turn, increased lung levels of the chemokine CCL5 in patients with asthma and in mouse models of asthma (1, 2) were presumed to cause further recruitment of inflammatory cells, especially eosinophils, into airway tissue and consequent worsening of airway disease. However, this view of CCL5, and chemokines in general, turns out to be quite naive, as underscored by an additional article in the current issue of the AJRCMB (3). In this new article, Koya and colleagues (pp 147–154) show that CCL5 selectively dampens the long-term effect of allergen challenge in mice (3). In this model, prolonged allergen exposure (out to 48 d after initial sensitization) led to airway hyperreactivity and mucous cell metaplasia, and administration of CCL5 decreased these traits, whereas treatment with anti-CCL5 antibody significantly increased them. Administration of CCL5 also caused an increase while anti-CCL5 antibody caused a decrease in BAL fluid levels of IFN-γ as well as IFN-γ-producing CD4 T cells. Moreover, anti–IFN-γ antibody treatment caused an increase in airway hyperreactivity. Together, the results suggest that CCL5 somehow stimulates the generation of IFN-γ–producing Th1 cells that protect against a prolonged allergic response. Whether concomitant changes in lung IL-12 levels are linked to this mechanism remains uncertain. Similarly, why this action takes place after longer- but not shorter-term allergen exposure still needs to be defined, but presumably relies on the delayed development of an activated Th1 cell population.

Is the upregulation of bradykinin B2 receptors by TGF-β1 one of the missing pieces in the “airway hyperresponsiveness” puzzle?

transforming growth factor (TGF)-β1 belongs to the TGF-β family of proteins corresponding to a set of pleiotropic secreted signaling molecules with unique and potent immunoregulatory properties ([10][1]). TGF-β1 is produced by every leukocyte lineage, including lymphocytes, macrophages, and

Prolonged allergen challenge in mice leads to persistent airway remodelling.

Inflammatory infiltrates, airway hyper-responsiveness, goblet cell hyperplasia and subepithelial thickening are characteristic of chronic asthma. Current animal models of allergen-induced airway inflammation generally concentrate on the acute inflammation following allergen exposure and fail to mimic all of these features. The aim of this study was to use a murine model of prolonged allergen-induced airway inflammation in order to characterize the cells and molecules involved in the ensuing airway remodelling. Moreover, we investigated whether remodelling persists in the absence of continued allergen challenge. Acute pulmonary eosinophilia and airways hyper-reactivity were induced after six serial allergen challenges in sensitized mice (acute phase). Mice were subsequently challenged three times a week with ovalbumin (OVA) (chronic phase) up to day 55. To investigate the persistence of pathology, one group of mice were left for another 4 weeks without further allergen challenge (day 80). The extended OVA challenge protocol caused significant airway remodelling, which was absent in the acute phase. Specifically, remodelling was characterized by deposition of collagen as well as airway smooth muscle and goblet cell hyperplasia. Importantly, these airway changes, together with tissue eosinophilia were sustained in the absence of further allergen challenge. Examination of cytokines revealed a dramatic up-regulation of IL-4 and tumour growth factor-beta1 during the chronic phase. Interestingly, while IL-4 levels were significantly increased during the chronic phase, levels of IL-13 fell. Levels of the Th1-associated cytokine IFN-gamma also increased during the chronic phase. In conclusion, we have demonstrated that prolonged allergen challenge results in persistent airway wall remodelling.

ISS inhibits expression of MMP-9 and MMP-2 in a mouse model of airway remodeling

Rationale MMPs are involved in the regulation of collagen deposition in the extracellular matrix. We investigated whether repetitive allergen challenge in mice induces expression of MMPs and TIMP-1 in the remodeled airway and whether ISS modulates expression of MMPs and TIMP-1. Methods Mice were repetitively challenged with OVA for 3 months to assess levels of MMP and TIMP expression (Elisa, immunohistochemistry). Levels of total lung collagen were measured by the Sircol soluble collagen assay. The effect of ISS on MMP and TIMP-1 expression was assessed by pretreating ova challenged mice with ISS every 2 weeks. Results Repetitive ova challenge induced a significant increase in the levels of lung MMP-9, MMP-2, and TIMP-1 (p=0.01). ISS treatment of ova challenged mice significantly reduced the levels of MMP-9,-2 and TIMP-1 compared to ova challenged mice not treated with ISS (p=0.01). Repetitive ova challenge induced a significant increase in the levels of lung collagen(p=0.01). ISS treatment of ova challenged mice significantly reduced the levels of lung collagen compared to ova challenged mice not treated with ISS (p=0.01, n=16). Conclusion Repetitive ova challenge induces increased levels of lung collagen which is associated with increased levels of expression of MMP-9, -2, and TIMP-1. ISS reduces lung collagen levels, as well as levels of MMP-9, -2 and TIMP-1, suggesting a role for ISS in inhibiting airway remodeling.

Role of prostaglandin I2 in airway remodeling induced by repeated allergen challenge in mice.

Recently, we demonstrated that prostaglandin (PG)I2 has a regulatory role in allergic responses through the receptor, IP; however, the role of PGI2 in airway remodeling associated with chronic airway inflammation has not been elucidated. In the present study, we examined the role of PGI2 in allergen-induced airway remodeling using IP gene-deficient mice. Mice were sensitized to ovalbumin (OVA) with alum, and exposed daily for 3 wk to aerosolized OVA. Twenty-four hours after the final antigen inhalation, bronchoalveolar lavage, biochemical, and histopathologic examinations were performed. In wild-type mice, prolonged allergen exposure in sensitized animals induced the increases in the numbers of inflammatory leukocytes (including eosinophils and lymphocytes), levels of T helper type 2 (Th2) cytokines (interleukin [IL]-4, IL-5, and IL-13), levels of OVA-specific immunoglobulin (Ig)E and IgG1 in serum, and amount of hydroxyproline in the right lungs associated with transforming growth factor-beta1 levels in bronchoalveolar lavage fluid. Moreover, goblet cell hyperplasia and subepithelial fibrosis were also appreciated after repeated allergen challenge. In contrast, the disruption of IP gene significantly augmented all these parameters. These findings suggest that PGI2 has a regulatory role in allergen-induced airway remodeling as well as airway eosinophilic inflammation, Th2 cytokine production and IgE production, and that a PGI2 agonist is a therapeutic approach for the treatment of airway remodeling in allergic asthma.

Inducible nitric oxide synthase inhibitors suppress airway inflammation in mice through down-regulation of chemokine expression.

Growing evidence demonstrates that inducible NO synthase (iNOS) is induced in the airways of asthmatic patients. However, the precise role of NO in the lung inflammation is unknown. This study investigated the effect of both selective and nonselective iNOS inhibitors in an allergen-driven murine lung inflammation model. OVA challenge resulted in an accumulation of eosinophils and neutrophils in the airways. Expression of iNOS immunostaining in lung sections together with an increase in calcium-independent NOS activity in lung homogenates was also observed after OVA challenge. Treatment with iNOS inhibitors from the day of challenge to the day of sacrifice resulted in an inhibition of the inflammatory cell influx together with a down-regulation of macrophage inflammatory protein-2 and monocyte chemoattractant protein-1 production. In contrast, eosinophilic and neutrophilic inhibition was not observed with treatment during the sensitization. Both treatments induced an increased production of Th2-type cytokines (IL-4 and IL-5) with a concomitant decrease in production of Th1-type cytokine (IFN-gamma). In vitro exposure of primary cultures of murine lung fibroblasts to a NO donor, hydroxylamine, induced a dose-dependent release of macrophage inflammatory protein-2 and monocyte chemoattractant protein-1. Our results suggest that lung inflammation after allergen challenge in mice is partially dependent on NO produced mainly by iNOS. NO appears to increase lung chemokine expression and, thereby, to facilitate influx of inflammatory cells into the airways.